Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-08-29T14:02:13Z No. of bitstreams: 1 2009 - Breno Almeida Soares.pdf: 7105040 bytes, checksum: 3b6aebf34151816545510b0506ed3412 (MD5) / Made available in DSpace on 2017-08-29T14:02:13Z (GMT). No. of bitstreams: 1 2009 - Breno Almeida Soares.pdf: 7105040 bytes, checksum: 3b6aebf34151816545510b0506ed3412 (MD5) Previous issue date: 2009-09-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / This work is part of a research project which investigates the utilization of abundant and accessible natural products in the synthesis of new molecules with potential activity against Chagas? disease. Recent studies carried out in our laboratory showed activity against Trypanosoma cruzi for piperine, a major component of Piper nigrum and for a series of its derivatives and analogues. Using bioisosterism as a strategy for molecular modification, we describe here the design, synthesis and antiparasitic evaluation of class of derivatives of 1,2,4-oxadiazole. The key step of the synthetic strategy used involved the SNAC reaction of the benzamidoxima with acid chlorides followed by cyclization, which allowed the preparation of eight new 1,2,4-oxadiazole The evaluation of the toxic activity of these new derivatives against epimastigote form of T. cruzi confirmed the bioisosteric relationship between the natural amide and the new products prepared, showing the oxadiazole 55 direct derived from piperine, as the most active compound in the series. / Este trabalho se insere numa linha de pesquisa que visa a utiliza??o de produtos naturais abundantes e access?veis na s?ntese de novas mol?culas com potencial atividade anti-chag?sica. Estudos recentes em nosso laborat?rio demonstraram a atividade antiparasit?ria da piperina e de uma s?rie de derivados e an?logos sobre o Trypanosoma cruzi, agente etiol?gico da doen?a de Chagas. Utilizando o bioisosterismo como estrat?gia de modifica??o molecular, descrevemos aqui o planejamento, a s?ntese e a avalia??o antiparasit?ria de derivados da classe dos 1,2,4-oxadiaz?is. A etapa-chave da estrat?gia sint?tica utilizada envolveu a rea??o de SNAC da benzamidoxima com cloretos de ?cidos, seguida de cicliza??o, que permitiu a prepara??o de oito novos 1,2,4- oxadiaz?is. A avalia??o da atividade t?xica destes novos derivados contra a forma epimastigota do T. cruzi confirmou a rela??o bioisost?rica entre a amida natural e os novos derivados preparados, evidenciando o oxadiazol 55 derivado direto da piperina, como o composto mais ativo da s?rie.